In step c though you should only add the first entry into /etc/apt/sources, since dell has changed the url to the repository for Etch already and removed the old stuff for Sarge. So still we need fis this, so do that:

apt-get install modutils

wget "http://linux.dell.com/dkms/debian/dkms_2.0.16.1-1_all.deb"
( if Dell ever removes the file, I will attach it here to this article )

dpkg -i dkms_2.0.16.1-1_all.deb

rm -rf dkms_2.0.16.1-1_all.deb

Right after you have done that, you can carry on with step d and follow the document to the end and you will have MPPE in your kernel!